Various ratchet drives are known in the art in which a ratchet gear is mounted on a support turnable about its axis and in which a drive arm is provided which may, for instance, be mounted tiltable about a forward and a return stroke about the axis of the ratchet gear and tiltably carrying a drive pawl engaging with a free end thereof the teeth of the ratchet gear to drive the latter through a given angle during the forward stroke of the drive arm, while moving rearwardly during the return stroke of the latter. These known arrangements need a holding pawl for preventing the ratchet gear from moving in the reverse direction while the drive arm moves along its return stroke. The drive arm may be tilted between its forward and its return stroke by fluid operated cylinder and piston means operatively connected thereto.
Such known ratchet drives may be used for many purposes and especially in a wrench for turning a threaded connector. In this case, the ratchet gear may be provided with a coaxial polygonal passage therethrough for engagement with a polygonal head of a threaded connector to be turned.
The evident disadvantage of such known ratchet drives is that the ratchet gear will be turned only during the forward stroke of the drive arm, while remaining stationary during the return stroke of the latter.